Children born by cesarean section are five times more likely to develop allergies than those born naturally when exposed to high levels of common household allergens, according to data presented during the 2013 Annual Meeting of the American Academy of Allergy, Asthma & Immunology in San Antonio.
Previous studies have indicated that mode of delivery during childbirth could alter neonatal immune responses and increase the risk for atopy.
To examine the relationship of delivery type to food allergen sensitization in early childhood, researchers from Henry Ford Hospital reviewed data from 572 children in the Detroit area Wayne County Health, Environment Allergy and Asthma Longitudinal Study (WHEALS) birth cohort at four age intervals — 1 month, 6 months, 1 year and 2 years.
Christine Cole Johnson
Women were enrolled during pregnancy and delivery mode was captured through medical record review. Blood samples were obtained near the child’s second birthday (mean age, 2.3 years).
Food sensitization was defined as having at least one specific immunoglobulin E test >0.35 kU/L to milk, egg or peanut. Mother’s atopic status was defined as having at least one specific IgE ≥0.35 kU/L to one of eight common allergens, according to the study abstract.
Among the WHEALS birth cohort, the cesarean section rate was 35.3%, and 40.9% of those children were sensitized to at least one food (peanut: 11.5%; egg: 24.3%; milk: 31%). Children delivered via cesarean section were more likely to be sensitized to at least one food (OR=1.5; 95% CI, 1.0-2.1).
Among infants with atopic mothers, the OR of food sensitization in those born by cesarean vs. vaginal delivery was 1.8 (P=.011), whereas no connection between mode of delivery and food sensitization was found in children of non-atopic mothers (OR= 1.0; P=.92).
“This further advances the hygiene hypothesis that early childhood exposure to microorganisms affects the immune system’s development and onset of allergies,” Christine Cole Johnson, PhD, MPH, chair of the department of health sciences at Henry Ford Hospital, said in a press release. “We believe a baby’s exposure to bacteria in the birth canal is a major influencer on their immune system.”
For more information:
Younus M. Abstract #82. Presented at: 2013 Annual Meeting of the AAAAI; Feb. 22-26, 2013; San Antonio.